Pesticidal composition containing 2, 3-pdioxanedithiol s, s-bis (phosphorodithioates) of halogenated alcohols



United States Patent PESTICIDAL COMPOSITION CONTAINING 2,3-P-DIOXANEDITHIOL S,S-BIS(PHOSPHORODITHIO- ATES) OF HALOGENATED ALCOHOLSAlbert H. Haubein, Christiana, Del., assignor to Hercules PowderCompany, Wilmington, Del., a corporation of Delaware No Drawing.Application August 30, 1954, Serial No. 453,139

12 Claims. (Cl. 167-33) This invention relates to new and useful organicthiophosphate compounds and to pesticidal compositions containing thesame.

The novel organic thiophosphate compounds of this invention have thegeneral formula in which each R represents a halo lower alkyl radical.

These organic thiophosphate compounds have pesticidal properties anddistinguish themselves in being highly toxic at low concentrationstoward certain pests.

The organic thiophosphate compounds of this invention are made byreacting 2,3-dichloro-p-dioxane or 2,3 dibromo-p-dioxane with thedesired diester of dithiophosphoric acid, the latter being the productof reaction of an alcohol or a mixture of alcohols of the formula ROH inwhich R is a halo alkyl radical of 1-4 carbon atoms and Pass. Thediester of dithiophosphoric acid may be reacted directly with the2,3-dihalodioxane or it may be reacted in the form of its salt or in thepresence of materials which sequester the hydrogen halide set free inthe reaction.

The methods ofmaking the products of this invention and methods of usingthe products as pesticides are more particularly described in thefollowing examples in which all parts and percentages are by weight.

Example 1 Tea stirred solution of 15.8 parts pyridine and 0.2 parthydroquinone in 200 parts benzene was added over a 15 minute period 60.0parts 0,0-bis(2-chloroethyl) dithiophosphoric acid. To the resultingsalt solution was then added 15.7 parts 2,3-dichloro-p-dioxane. Themixture was then refluxed for 6 hours during which time pyridinehydrochloride separated. At the end of this time, water was added todissolve the water soluble salts and the organic layer was furtherpurified by washing first with sodium hydroxide solution and then withwater. After drying over sodium sulfate, the solvent benzene was removedunder reduced pressure and the residue was topped at 85 C./0.5 mm. Theresidue, which was the bis(bis(2-chloroethyl) dithiophosphate) ofp-dioxane-2,3-dithiol, also designated 2,3-p-dioxanedithiolS,S-bis(0,0-bis (2-chloroethyl) phosphorodithioate) amounted to 34.7parts and had a purity of about 86% based on sulfur analysis.

An emulsifiable concentrate of the residue was made by mixing 1 gram ofthe residue with 1 ml. benzene and 1 ml. sorbitan monolauratepolyoxyalkylene derivative (Tween 20). This concentrate was then dilutedwith water to form dispersions of the residue in water varying inconcentration from 1.0% to 0.0025%. The dispersions were then tested fortheir toxicity to caged insects and to mites not only by spraying theinsects but by 2,725,330 Patented Nov. 29, 1955 spraying the plantsalone as well for the purpose of determining residual toxicity. Standardtest methods were used for obtaining the results set forth below.

When pea aphids were sprayed with a 0.05% emulsion of the composition ofthis example and placed on pea seedlings sprayed simultaneously with thesame emulsion there resulted 30% mortality in 48 hours.

Activity tests were also run by spraying'lima bean seedlings infestedwith two-spotted mites to run off with 0.1% aqueous emulsion. Thereresulted'80% mortality to the mites after 5 days.

Example 2 Example 3 Bis(fluoroethyl) dithiophosphoric acid was preparedby the reaction of 2-fluoroethanol on phosphorus pentasulfide and wasthen reacted with 2,3-dichloro-p-dioxane in benzene solution to producethe bis(bis(fluoroethyl) dithiophosphate) of p-dioxane-2,3-dithiol. Thisproduct was then made into a concentrate with benzene and Tween 20 anddiluted to emulsions of various concentrations. These insecticidalcompositions were then tested for their toxicity to insects and mitesboth by contact and by treating plants on which the insects and mitesnormally live. A 0.1% emulsion showed a 66% kill against the housefly; a1% emulsion showed kill when applied to lima bean plants infested withMexican bean beetles; a 0.1% emulsion showed 100% kill against peaaphids on pea seedlings; and a 0.1% emulsion showed a 100% kill oftwo-spotted mites on lima bean plants.

The organic dithiophosphate compounds of the formula are those in whicheach R is the same or a diiferent halohydrocarbon radical such asmonochloroethyl, monchloropropyl, dichloroethyl, trichloroethyl,chloroisopropyl, dichloropropyl, trichloropropyl, fl-fluoroethyl,B-bromoeth-yl, and the like. The radicals which are especially effectiveare those with a molecular weight less than about 135. The preferredcompounds are those containing the chloroalkyl radical having 1-4 carbonatoms. 7

In producing the compounds of this invention the reaction between the2,3-dichlor0-p-dioxane or 2,3-dibromop-dioxane and the ester ofdithiophosphoric acid or its salt is carried out by heating the tworeactants at a temperature at which reaction takes place but below thedecomposition temperature in the range of 20 to 200 C., preferably inthe range of 30 to C. The reactants may The reaction is preferablycarried out in nonaqueous media. Organic solvents are desirable to aidin control of the reaction. Suitable solvents include benzene, toluene,xylene, cyclohexane, hexane, anhydrous alcohol solvents and dioxane. Itis preferable to use hydrocarbon solvents when using an amine salt ofthe dithiophosphoric acid ester or when using an amine or ammonia as asequestering reagent. After the reaction is complete the solvent isreadily removed by distillation.

When the diester of dithiophosphoric acid is used as the free acid inthe reaction with the 2,3-dihalo-p-dioxane, hydrogen halide which isliberated is preferably sequestered by adding a material to combine withthe hy drogen halide as formed. It is convenient to use pyridine forthis purpose. However, in its place other tertiary organic amines may beused, and they may be added in equivalent amount at the beginning of thereaction or gradually during the course of the reaction. Likewise, theamine can be reacted with the diester of the dithiophosphoric acid priorto carrying out the reaction with the 2,3-dihalo-p-dioxane as inExample 1. Amines which can be used include pyridine, tertiary alkylamines such as trimethyl amine, tributyl amine, triamyl amine, dirnethylaniline and the like. Inorganic bases may also be used. These includeammonia, alkali metal hydroxides, carbonates and bicarbonates, andalkaline earth metal hydroxides and carbonates.

As in the case of organic bases, the inorganic bases may also be usedfirst to form a salt of the ester of the dithiophosphoric acid. When thesalt of the ester of dithiophosphoric acid is usedas the reactant, it ispreferable to use a salt which is soluble in the organic solvent usedfor the reaction. The organic salts of amines are particularlysatisfactory because of the good solubility of these salts in thenonreactive hydrocarbon solvents. When the free acid is reacted with the2,3-dihalodioxane, the alkaline material is preferably added graduallyas needed but it can be added all at once if desired. Ammonia issuitably added gradually as a gas, the solids are suitably added infinely divided form.

The dithiophosphoric acid ester is produced by reacting the halo loweraliphatic alcohol, which is to form a part of the ester, with P235preferably in a nonreactive solvent such as benzene, toluene, xylene,hexane or cyclohexane and removing the H28 which is liberated. Thereaction is carried out at any temperature in the range of 50 to 120 C.,selecting the lowest practical temperature without decomposition. Ifdifferent radicals are desired for the various R radicals, a mixture ofalcohols may be used in the production of the dithiophosphoric acidester. Likewise, dithiophosphoric acid esters produced from differentalcohols can be mixed for use in the reaction with the2,3-dihalo-p-dioxane. The esters of dithiophosphoric acid used inpreparation of the compounds of this invention are thus made fromindividual halo alcohols or mixtures of halo alcohols having 1-4 carbonatoms. Included among such alcohols are: ,G-chloroethanol,,3-fiuoroethanol, ,B-bromoethanol, 6- chloropropanol, ,B-fluoropropanol,ubromopropanol, dichloroethanol, trichloroethanol, dichloropropanol,trichloropropanol, chloropropanol-Z, fiuorobutanol, and the like.

The methods by which the products of this invention are isolated willvary slightly with the reactants used and the product produced. In someinstances the halide salt split out in the reaction separates and can befiltered off. In other instances the halide salt is best removed bywashing with water. The excess salt of the ester of dithiophosphoricacid is also removed by the water wash. The benzone or other solvent isthen removed by distillation leavr ing insecticidally active residue.Further purification by selective solvent extraction or by adsorptiveagents such as activated carbon, or clays, can precede the removal ofthe solvent. Likewise, an organic solvent can be added to aid in thepurification by adsorptive agents.

4 However, the product is generally satisfactory for use as a pesticidewithout further purification.

The compounds of this invention are used as the sole toxic agent inpesticidal formulations or in admixture with other toxicants formodification of the properties of the individual toxicants. They may beused, for example, in admixture with toxaphene, DDT, Thanite, chlordane,rotenone, pyrethrum and the like in many of-the formulations suggestedbelow.

The compounds of this invention are made into pesticidal compositionsfor use againstinsects and mites by dilution with an insecticidaladjuvant as a carrier therefor, by dispersing in an organic solvent, orin water, or by diluting with a solid insecticidal adjuvant 'as acarrier. Dispersions containing a surface active dispersing agent havethe advantage of spreading the toxic substance more effectively over theplant surface. Dispersions in organic solvents include dispersions inalcohols, pine oil, hydrocarbon solvents, difluorodichloromethane, andsimilar organic solvents. The compounds of this invention are also usedin aerosol formulations in which difluorodichloromethane and similaraerosol propellants form the propellant vehicle.

Aqueous dispersions are made up from the compounds of this invention, asurface active dispersing agent and water as the essential ingredients.The amount of the compounds of this invention in the aqueous dispersionswhen diluted for spraying of plants will be in the range of about 10% toabout 0.001% of the aqueous dispersion.

The aqueous dispersion will ordinarily be made up from a concentrate,and the concentrate will be dispersed in water to the properconcentration for application to the plants to be treated in the field.The concentrate is composed essentially of the compound of thisinvention and a surface active dispersing agent. The concentrate mayalso contain sufiicient amounts of organic solvents to aid in effectivedispersion. The amount of surface active dispersing agent used isusually at least 5% of the amount of toxic compound in the concentrate.

Suitable surface active dispersing agents for use in the compositions ofthis invention are those disclosed in Chemistry of Insecticides,Fungicides, and Herbicides (l. c., pages 280287) for use with knowninsecticides and include neutral soaps of resin, alginic and fatty acidsand alkali metals or alkyl amines or ammonia, saponins, gelatins, milk,soluble casein, flour and soluble proteins thereof, sulfite lye, ligninpitch, sulfite liquor, long-chain fatty alcohols having 12-18 carbonatoms and alkali metal. salts of the sulfates thereof, salts of sulfatedfatty acids, salts of sulfonic acids, esters of long-chain fatty acidsand polyhydric alcohols in which alcohol groups are free, clays such asfullers earth, China clay, kaolin, attapulgite, and bentonite andrelated hydrated aluminum silicates having the property of forming acolloidal gel. Among the other surface active dispersing agents whichare useful in the compositions of this invention are theomega-substituted polyethylene glycols of relatively longchain length,particularly those in which the omega substituent is aryl, alkyl, oracyl. Compositions of the toxic material and surface active dispersingagent will in some instances have more than one surface activedispersing agent for a particular type of utility, or in addition to asurface active dispersing agent, hydrocarbons such as kerosene andmineral oil will also be added as improvers. Thus, the toxic materialmay contain a clay as the sole adjuvant or clay and hydrocarbon, or clayand another surface active dispersing agent to augment the dispersingaction of the clay. Likewise, the toxic material may have water admixedtherewith along with the surface active dispersing agent, sufficientgenerally being used to form an emulsion. All of these compositions oftoxic material and surface active dispersing agent may contain inaddition synergists and/or adhesive or sticking agents.

What I claim and desire to protect by Letters Patent is:

1. As a new composition of matter a compound of the formula in whicheach R represents a haloalkyl radical having 1-4 carbon atoms.

2. As a new composition of matter a compound of the formula s CH2on-si'woomomomom 3. As a new composition of matter a compound of theformula s Cfiz CHS1 (OCHiCHzC1)2 s 052 OHSi "(0CH2CHzCl)n 4. As a newcomposition of matter a compound of the formula ll e g \CHSP(OCH2CH7F)25. As a new composition of matter a compound of the formula S a OLHISi(0 01120 C192 Ca l I CH: on-siwoomo 013):

12. A pesticidal composition comprising the compound of claim 11 and aninsecticidal adjuvant.

References Cited in the file of this patent UNITED STATES PATENTS2,529,304 Mikeska Nov. 7, 1950 2,531,129 Hook Nov. 21, 1950 2,542,604Weisel Feb. 20, 1951 2,565,920 Hook Aug. 28, 1951 2,565,921 Hook Aug.28, 1951

1. AS A NEW COMPOSITION OF MATTER A COMPOUND OF THE FORMULA